--  @testpoint:opengauss关键字extract(非保留)，作为函数名

--关键字不带引号-失败
drop function if exists extract;
create function extract(i integer)
returns integer
as $$
begin
    return i+1;
end;
$$ language plpgsql;
/
--关键字带双引号-成功
drop function if exists "extract";
create function "extract"(i integer)
returns integer
as $$
begin
    return i+1;
end;
$$ language plpgsql;
/
drop function "extract";
--关键字带单引号-合理报错
drop function if exists 'extract';
create function 'extract'(i integer)
returns integer
as $$
begin
    return i+1;
end;
$$ language plpgsql;
/
--关键字带反引号-合理报错
drop function if exists `extract`;
create function `extract`(i integer)
returns integer
as $$
begin
    return i+1;
end;
$$ language plpgsql;
/